1. Field of the Invention
The subject matter of the present invention is related to an adjuster for establishing the clearance position or non-braking position of a vehicular brake pad assembly and more particularly to constructing of this adjuster to eliminate corrosion due to contamination by water and also eliminate contamination by dust and dirt.
2. Description of the Related Art
It is a requirement to slow and stop a vehicle. In order to slow and stop a vehicle, a brake is used. Typical vehicles would be automobiles, trucks and trailers. Brakes that are utilized in conjunction with vehicles take a variety of forms. Each form of brake is of a frictional type in which a fixed surface is brought into contact with a moving part which is to be slowed or stopped. The fixed surface and the moving surface are rubbed together and energy stored in the moving part is converted into heat and dissipated to the atmosphere. The loss of energy from the moving part is accompanied by a desired reduction of movement. Vehicular brakes generally take two forms that being a drum brake assembly or a disc brake assembly.
In the internal expanding type of drum brake assembly, two brake shoes on a fixed mounting are pushed against the inside of a rotating drum to create the required braking force. Generally, the shoes are moved hydraulically. On a drum type of brake, one brake shoe is self energizing and the other shoe is not. If the drum rotation is clockwise, it tends to pull the shoe on the right harder against the inner surface so that the braking affect is increased. This shoe is called the leading shoe. The other shoe, which is the trailing shoe, is pushed off by the transfer from rear axle to front axle during normal braking.
Within a drum brake assembly, there is a need to locate the brake linings just at a non-braking position so that only a minimal amount of movement is required of the brake pads in order to achieve a braking position. In order to achieve this, included within the brake drum assembly is an adjuster and this adjuster is to be manually activated to move the brake pads tightly against the drum which will establish the braking position. The adjuster is then loosened until the brake pads assume a clearance position which will permit free rotation of the moving part, which is the wheel, relative to the fixed part, which is the drum.
Drum brake assemblies rather than disc brake assemblies, are commonly used in conjunction with trailers, and specifically boat trailers. It is common for boat trailers to be submerged within water on the launching ramp for the boat. When the water comes into contact with the adjuster mechanism of the brake drum assembly, the moisture will quickly cause corrosion of the adjuster with the result that in a short period of time the adjuster becomes inoperable and requires replacement. If the water happens to be salt water, the problem is magnified as salt water is especially corrosive. The time period which will pass before non-operation of the adjuster is even shortened than if it were fresh water.
There is a need to construct the adjuster mechanism of a brake drum assembly so that this adjuster mechanism is free from corrosion due to contamination with any kind of water and also free from contamination by dust and dirt.
The basic embodiment of the present invention comprises an adjuster for establishing the non-braking position of a vehicular brake pad assembly. The adjuster includes a sleeve which has an internal chamber. Within the internal chamber is located female screw threads. The internal chamber has an entry opening. The sleeve terminates in a first outer end with the first outer end adapted to connect with a first brake pad unit of the brake pad assembly. A shaft has a series of male screw threads with these male screw threads to be located within the internal chamber of the sleeve with the male screw threads to engage with the female screw threads. The shaft has a second outer end located exteriorly of the internal chamber. The second outer end is adapted to connect with the second brake pad unit of the brake pad assembly. A star wheel is mounted on the second outer end with the star wheel being manually engagable to affect turning of the shaft relative to the sleeve with the male screw threads moving relative to the female screw threads. A seal is located within the internal chamber and establishes a watertight and dust tight connection between the shaft and the sleeve preventing water and dust from entering the internal chamber.
A further embodiment of this invention is where the basic embodiment is modified to where there is a non-threaded area included within the internal chamber of the sleeve.
A still further embodiment of this invention is where the basic embodiment is modified by the first outer end being closed.
In yet a still further embodiment of this invention, the basic embodiment is modified to where the seal is defined as being an O-ring.
In a still further embodiment of this invention, the basic embodiment is modified by the seal being located directly adjacent the entry opening into the internal chamber.
In yet a still further embodiment of this invention, the basic embodiment is modified by the first outer end being non-rotatably fixed relative to the first brake pad unit.
In yet a still further embodiment of this invention, the basic embodiment is modified to where the second outer end is non-rotatably fixed relative to the second brake pad unit.
In yet a further embodiment of this invention, the basic embodiment is modified by the seal being mounted on the sleeve.
In yet a further embodiment of this invention, the basic embodiment is modified by the sleeve and the shaft both being constructed of stainless steel.